Platelet-Rich Plasma Preparations for Biological Therapy: Applications and Limits

Platelets are anucleate blood cells characterized as primary effectors of hemostasis. The rationale for the therapeutic use of platelets as a surgical adjuvant is to make platelet-derived factors locally available for tissue healing. Several platelet-derived growth factors have been recently characterized, able to favor both wound healing and angiogenesis. Biological therapies using platelet-rich plasma (PRP) preparations are currently being used, making it essential to expand our knowledge on the sequential events that characterize PRP action. Studies on the efficacy of PRP in human subjects are still scarce, probably because of the relatively recent clinical applications of PRP. In some case control studies and in several noncontrolled clinical trials, PRP has been found effective. However, the results of most studies are hampered by relevant confounding variables such as the variations of PRP characteristics even in patients with similar platelet counts. PRP essentially acts as a growth factor reservoir, inducing mitogenesis, chemotaxis, and angiogenesis at the site of application. However, notwithstanding several different characteristics between them, all platelet-enriched products are called PRP, which makes the distinctions difficult. Hence, although PRPs represent a promising tool of clinical application, many questions are still open, such as the appropriate indications for its clinical use as well as the effective concentrations and quantities for each product to be used in each therapeutic situation.